In a wireless communication system, when a terminal connects to a base station, the base station allocates a unique identifier in order to identify the terminal. Thus, a unique identifier is used to identify each terminal in a common downlink control channel shared by all terminals and is included in control data. In the case of an LTE system, an identifier for the control channel is referred to as RNTI. An example where the identifier is used for a control channel is described below with reference to FIGS. 1 and 2.
FIG. 1 illustrates a process of generating control information in a wireless communication system according to the related art.
Referring to FIG. 1, a 16-bit CRC 120 is attached to a DCI 110 for error detection from a terminal that receives the control information. In addition, an identifier 130 for identifying each terminal is XOR-masked for the CRC 120. The control information including the DCI 110 and a tail bit 140 are encoded and modulated transmitted through a wireless channel. In the case of an LTE system, a channel over which the control information is transferred is referred to as PDCCH.
FIG. 2 illustrates a process of analyzing control information in a wireless communication system according to the related art.
When the terminal demodulates and decodes the control information, a decoded DCI 210 and a decoded tail bit 240 are obtained. In order to determine whether the DCI 210 received is control information for the terminal, that terminal generates CRC 220 from the decoded DCI 210, XOR operates on the CRC 220 and the tail bit 240, and further XOR operates on an identifier 230. When the received DCI 210 has no error and the identifier 230 matches an identifier used when generating control information by a base station, a value obtained by XOR operation is zero. Thus, the terminal may determine whether the DCI 210 received is control information for that terminal.
As described above, the control information may be decoded by using the identifier of a corresponding terminal. That is, if it is possible to perceive an identifier allocated to another terminal, a terminal may check control information for another terminal. Thus, as illustrated in FIG. 3, when a terminal located at a cell border experiences interference with a neighboring base station, the terminal may check control information for another terminal transmitted by the neighboring base station and utilize the control information for removing interference.
FIG. 3 illustrates a condition in which there is interference with a neighboring base station in a wireless communication system according to the related art.
Referring to FIG. 3, a terminal 310 receives a signal from a serving base station 320. However, since the terminal 310 is located at the cell border of the serving base station 320, a signal from the neighboring base station 330 is transmitted to the terminal 310. That is, the terminal 310 receives an interference signal from the neighboring base station 330. In this case, the terminal 310 may use identifiers allocated to terminals accessed to the neighboring base station 330 to decode control information transmitted from the neighboring base station 330 and utilize the identifiers for removing interference.
In order to check control information transmitted from the neighboring base station 330, the terminal 310 should obtain the identifiers of other terminals or perform blind detection. The identifiers of other terminals may be provided directly through the broadcasting channel of the neighboring base station 330 or indirectly through the serving base station 320. In this case, overhead increases depending on the number of terminals accessed to the neighboring base station 330. On the other hand, in the case of blind detection, since there is a need to perform decoding on all identifiers that may be used, the number of times that decoding is performed is large and moreover, a decoding failure probability is also high. In this case, the terminal 310 experiences a waste of power.
Thus, there is a need to suggest an alternative for efficiently providing or determining information on identifiers allocated to the terminals of a neighboring base station used for removing interference.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.